cat Català ON D(-1)- Quadruples Ciprian Bonciocat, Nicolae Cipu, Mihai Mignotte, Maurice info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2012 Diophantine m-tuples Pell equations Linear forms in logarithms Publicacions matemàtiques http://ddd.uab.cat/record/91306 10.5565/PUBLMAT_56212_02 02141493v56n2p279 oai:ddd.uab.cat:91306 Tots els drets reservats http://www.europeana.eu/rights/rr-f/ Quadruples (a; b; c; d) of positive integers a < b < c < d with the property that the product of any two of them is one more than a perfect square are studied. Improved lower and upper bounds for the entries b and c are established. As an application of these results, a bound for the number of such quadruples is obtained.